This invention relates to processes for preparing pigment granules and to processes for dyeing landscaping and/or construction materials.
In many situations landscaping and/or construction materials may need to be dyed so as to impart a desired color to the material. By way of example, bark and/or wood mulch and/or concrete may need to be dyed so as to impart a desired color to the material and thereby render the material more pleasing in an architectural setting.
A number of different pigments are known in the art for mixing with landscaping and/or construction materials so as to impart the desired color to those construction materials. By way of example, iron oxides are capable of providing different colors commonly of interest (e.g., Red Fe2O3, Yellow Fe2O3.H2O, Black Fe3O4), and have the additional advantage that they may be effectively dispersed throughout the landscaping and/or construction material with the presence of ordinary water.
Unfortunately, however, iron oxide pigments generally come in the form of a fine powder which creates a number of problems during use. For one thing, pigment dust tends to migrate, soiling human beings, equipment and the surrounding premises. In addition, when the pigment powder is stored for any length of time, it tends to clump together into masses which are no longer freely flowable, thus complicating mixing of the pigment powder with the landscaping and/or construction materials which are to be dyed.
As a result, one object of the present invention is to provide a novel process for preparing compacted pigment granules which will remain free flowing after storage for a reasonable length of time, yet may thereafter be effectively dispersed throughout the landscaping and/or construction material with the presence of ordinary water.
Another object of the present invention is to provide a novel process for preparing encapsulated pigment granules which will remain free flowing after storage for a reasonable length of time, yet may thereafter be effectively dispersed throughout the landscaping and/or construction material with the presence of ordinary water.
And another object of the present invention is to provide a novel process for dyeing landscaping and/or construction materials using the aforementioned compacted pigment granules.
And another object of the present invention is to provide a novel process for dyeing landscaping and/or construction materials using the aforementioned encapsulated pigment granules.
These and other objects are addressed by the present invention, which provides a process for preparing compacted pigment granules, a process for preparing encapsulated pigment granules, and a process for dyeing landscaping and/or construction materials using the same.
In one form of the invention, there is provided a novel process for preparing compacted pigment granules, comprising the steps of: (1) loading 1000 kg to 3000 kg of iron oxide powder having a grain size of not less than 0.8 microns, at a temperature of 15-20 degrees C., into a mixer rotating at a speed of 1-25 rpm; (2) spraying, while the mixer is rotating, liquid binder solution onto the cascading pigment powder, where the liquid binder solution is made by mixing 200-850 liters of water with 2.5-15 kg of polyvinyl alcohol binder powder, and where the liquid binder solution is sprayed at a rate of 10-50 gallons per hour, for 1-4 hours, whereby the cascading pigment powder is compacted into dense granules of approximately 0.30-1.20 mm diameter and having a moisture content of approximately 10-14%; and (3) directing, while the mixer is rotating, heated air at a temperature of 200-600 degrees C. onto the compacted pigment granules, so that the compacted pigment granules are dried at a temperature of approximately 50-100 degrees C., and continuing this process for approximately 2-3 hours until the moisture content of the compacted pigment granules is reduced to approximately 2% or less, whereupon the compacted pigment granules are removed from the mixer.
In another form of the invention, there is provided a novel process for preparing encapsulated pigment granules, comprising the steps of: (1) loading 1000-3000 kg of iron oxide powder having a grain size of not less than 0.8 micron, at a temperature of 15-20 degrees C., into a mixer rotating at a speed of 1-25 rpm; (2) rotating the mixer for approximately 0.5-2.0 hours, with the pigment powder cascading within the mixer so as to result in the formation of pigment granules of approximately 0.3-1.20 mm diameter; (3) spraying, while the mixer is rotated, liquid encapsulation solution onto the cascading pigment granules, where the liquid encapsulation solution is made by mixing 200-850 liters of water with 2.5-15 kg of polyvinyl alcohol encapsulation powder, and where the liquid encapsulation solution is sprayed at a rate of 40-200 liters per hour, for 1-4 hours, whereby the liquid encapsulation solution encapsulates the cascading pigment granules, with the encapsulated pigment granules having a diameter of approximately 0.30-1.20 mm diameter and a moisture content of approximately 10-14%; and (4) directing, while the mixer is rotating, heated air at a temperature of 200-600 degrees C. onto the encapsulated pigment granules, so that the encapsulated pigment granules are dried at a temperature of approximately 50-100 degrees C., and continuing this process for approximately 2-3 hours until the moisture content of the encapsulated pigment granules is reduced to approximately 2% or less, whereupon the encapsulated pigment granules are removed from the mixer.
In another form of the invention, there is provided a novel process for dyeing landscaping and/or construction materials using compacted pigment granules, comprising the steps of: (1) preparing compacted pigment granules by (i) loading 1000-3000 kg of iron oxide powder having a grain size of not less than 0.8 micron, at a temperature of 15-20 degrees C., into a mixer rotating at a speed of 1-25 rpm; (ii) spraying, while the mixer is rotating, liquid binder solution onto the cascading pigment powder, where the liquid binder solution is made by mixing 200-850 liters of water with 2.5-15 kg of polyvinyl alcohol binder powder, and where the liquid binder solution is sprayed at a rate of 40-200 liters per hour, for 1-4 hours, whereby the cascading pigment powder is compacted into dense granules of approximately 0.30-1.20 mm diameter and having a moisture content of approximately 10%-14%; and (iii) directing, while the mixer is rotating, heated air at a temperature of 200-600 degrees C. onto the compacted pigment granules, so that the compacted pigment granules are dried at a temperature of approximately 50-100 degrees C., and continuing this process for approximately 2-3 hours until the moisture content of the compacted pigment granules is reduced to approximately 2% or less, whereupon the compacted pigment granules are removed from the mixer; and
(2) mixing the compacted pigment granules with the landscaping and/or construction materials in an environment where water is present, whereby the compacted pigment granules will break down and release their pigment powder for mixing with the landscaping and/or construction materials, whereby to dye the same.
In another form of the invention, there is provided a novel process for dyeing landscaping and/or construction materials using encapsulated pigment granules, comprising the steps of: (1) preparing encapsulated pigment granules by (i) loading 1000-3000 kg of iron oxide powder, at a temperature of 15-20 degrees C., into a mixer rotating at a speed of 1-25 rpm; (ii) rotating the mixer for approximately 0.5-2.0 hours, with the pigment powder cascading within the mixer so as to result in the formation of pigment granules of approximately 0.30-1.20 mm diameter; (iii) spraying, while the mixer is rotated, liquid encapsulation solution onto the cascading pigment granules, where the liquid encapsulation solution is made by mixing 200-850 liters of water with 2.5-15 kg of polyvinyl alcohol encapsulation powder, and where the liquid encapsulation solution is sprayed at a rate of 40-200 liters per hour, for 1-4 hours, whereby the liquid encapsulation solution encapsulates the cascading pigment granules, with the encapsulated pigment granules having a diameter of approximately 0.30-1.20 mm diameter and a moisture content of approximately 10-14%; and (iv) directing, while the mixer is rotating, heated air at a temperature of 200-600 degrees C. onto the encapsulated pigment granules, so that the encapsulated pigment granules are dried at a temperature of approximately 50-100 degrees C., and continuing this process for approximately 2-3 hours until the moisture content of the encapsulated pigment granules is reduced to approximately 2% or less, whereupon the encapsulated pigment granules are removed from the mixer; and (2) mixing the encapsulated pigment granules with the landscaping and/or construction materials in an environment where water is present, whereby the encapsulated pigment granules will break down and release their pigment powder for mixing with the landscaping and/or construction materials, whereby to dye the same.